Motor and ignition safety control system for liquid fuel burners



June 1954 N; .1. MOSELY MOTOR AND IGNITION SAFETY CONTROL SYSTEM FORLIQUID FUEL BURNERS Filed Nov. 27, 1951 INVENTOR. 3km M M M ATTORNEYPatented June 15, 1954 MOTOR AND IGNITION SAFETY CONTROL SYSTEM FORLIQUID FUEL BURNEBS Neal J. Mosely,

gheny County, Corporation,

Mount Lebanon Township, Alle- Pa., assignor to Detroit Controls acorporation of Michigan Application November 2'7, 1951, Serial No.258,339

8 Claims.

This invention relates to new and useful improvements in control systemsfor liquid fuel burners and more particularly to a primary controlsystem which is constructed of a minimum number of control parts.

In the past, many types or control systems, devices and circuits havebeen proposed for controlling the operation of liquid fuel burners, butsubstantially all of those have involved the use of very complicatedcircuits involving many switches, relays, and complicated timingmechanisms. In this invention there is provided a control system havinga minimum number of operating control parts to provide for maximumsimplicity and eirlciency in operation.

Accordingly, it is one object of this invention to provide a new andimproved control circuit for liquid fuel burners.

Another object is to provide a control circuit for liquid fuel burnershaving as few control switches and as simple a timing mechanism aspossible.

Another object is to provide a liquid fuel burner control system whichwill turn on a burner motor and ignition, after a predetermined timeturn oil the ignition, and if no flame occurs in the burner by the timethe ignition is turned off, will, after a predetermined further periodof time, turn off the burner motor, all with a minimum number of controlswitches and circuits.

Another object is to provide a liquid fuel burner control circuit andcontrol devices therefor which are simply and inexpensively constructedand assembled.

Other objects will become apparent from time to time throughout thespecification and claims as hereinafter related.

This invention comprises the new and improved construction andcombination of parts and their operating relationship each to each,which will be described more fully hereinafter and the novelty of whichwill be particularly pointed out and distinctly claimed.

In the accompanying drawing, to be taken as part of this specification,there is clearly and fully illustrated a preferred embodiment of thisinvention, in which drawing the figure shows in more or lessdiagrammatical form a control system for liquid fuel burners which isthe subject of this invention.

Referring to the drawing by characters of reference there is shown aliquid fuel burner IIlI having a burner motor I02 and an electric sparkignition 503. There is provided a transformer IM having a primary I015supplied from a high r spring I38 and 6 2. voltage power source Hit andhaving a secondary coil Illl. From the high voltage power source I136the wire H13 connects to the contact arm H8 of a switch H9. The switchH9 comprises contact arms H8 and I26 carrying normally closed contactsHI and I22, respectively, biased into initial engagement with eachother. From the wire I08, the wire H6 connects to one side of the burnermotor IE2. From the contact arm I26 of the switch us a wire !23 connectsto one end portion of the primary coil I24 of the ignition transformerI25. The ignition transformer I25 has a secondary coil mi and wires i2?and I28 leading therefrom to the spark ignition W3. The other endportion of the ignition primary coil its is connected as at E29 to areturn wire I30 from the burner motor I62 which is connected to thecontact arm i3i of a switch H2. The switch I32 comprises contact armsl3l and I33 carrying contacts H4 and I35, respectively. The contact armI33 is biased toward engagement of the contacts E34 and I35 but isrestrained by engagement with a stop I66. The contact arm I3! is biasedaway from the contact arm I33 and is engaged by a thrust transmittingmember MI. The contact arm N3 is connected by a wire I36 back to theother side of the high voltag power source I05. There is provided a snapmechanism I31 which is co-operable with the contact arm I33 and isoperable upon predetermined movement in one direction to snap the armE33 away from the arm I3 I. The snap mechanism I31 may be any suitablesnap mechanism, but for the purposes of this disclosure is shown as anovercenter a suitable adjustment mechanism therefor such as anadjustable screw I39, The adjustment screw I39 is operable to vary therelation of the spring I38 to the contact arm I33. The compressive forceof spring l38 biases the contact arm I33 toward the contact arm I3I andinto engagement with the stop its. A reset member Hit is provided inoverlying relation to the contact arm I33 to reset the same from anovercenter snapped open position. The contact arm H8 is biased formovement along with the contact arm I20 of the switch I It which ismoved by a suitable thrust transmitting member I42 and which transmitsmovement through member MI to the contact arm I3I of the switch I32.There is provided a timing means Hi l, which comprises a bi-metal memberI45 which is operated in accordance with the heat output of a resistanceheater I46 and the force against which the member I45 must work. Sincethe bimetal member I45 warps at a rate which is determined by the 3 rateof heat input and the force against which it works, and since theheating of the bimetal by the resistance heater I46 is a function of thetime that the heater was energized, it is apparent that the timingoperation of the bimetal may be adjusted by varying either the distancewhich it must move or the force against which it must work. The screwI39 is operable to adjust the compressive force exerted by the springI38 and thus varies the timing operation by varying the force againstwhich the bimetal must work. If the compression of spring I38 isincreased the bimetal must warp with a greater force, which requires alonger heating period. Similarly the spring I38 could be adjusted tovary the snap point of the arm I33 by varying the distance which thatarm must move before snapping over center. The resistance heater I46 isconnected to one side of the transformer secondary II]? by a wire I48and is connected by wires I49, I50 and II to the fixed contacts I52 andI53 of a singlepole, double-throw switch I54. A resistor I55 is providedin circuit between the wires I49 and I5I to modify the operation of theresistance heater I45 for the timing means I44. The movable pole I56 ofthe switch I54 carries contacts I57 and I58 cooperable with fixedcontacts I52 and I53, respectively, and is connected by wire I59 to afixed contact I60 of a room thermostat IfiI. The switch operating poleI56 of the switch I54 is operated by a suitable flame responsive meansI52 such as a bi-metal helix positioned for response to flametemperature in the burner stack I53. The room thermostat It! has asuitable temperature responsive member such as a bimetal I64 connectedby a wire I65 to the other side of the transformer secondary I01 andcarries a movable contact I56 cooperable with the fixed contact I60.

Operation In operation this system functions generally as follows:

The resistance heater I46 and bi-metal member I45 co-operate to form anelectro-thermal timer for operating the switches H9 and I32.

fected appreciably by burner temperature. When the room thermostatcontacts I60 and I 65 are closed calling for heat, a circuit iscompleted from the transformer secondary I01 through wire I45,resistance heater I46, wire I49, wire I50, contacts I52 and I5? ofswitch I54, wire I59, contacts I60 and I65 of the thermostat IIiI,thermostat blade I54, and wire I65, completing the connection to thetransformer secondary I07. With this circuit completed, the heat outputof the heater I45 will cause the bi-metal I45 to move at a ratedependent upon the heat output of the heater I45, the type of bi-metalused in the member I45, and the resistance against which the bi-metalmember I45 must operate. As the bi-metal member I 45 is moved upwards,it moves the thrust member I42 against the contact arm I and thus movesthe contact arm I 3| to move the switch contact I34 into engagement withcontact I35. When the contacts I34 and I35 are brought into engagement,a high voltage circuit is completed from the power source I06 by way ofwire I58, contact blade I I8, contacts I2I and I22, and contact bladeI20 to "wire I23 connected to the ignition I24. From wire I08 adjacentthe switch III the circuit divides and part is connected through theignition and part through the burner motor. The circuit through theburner motor extends from wire I58 by way of wire H6. The circuitthrough the ignition was previously described. The burner and ignitioncircuits join again at point I 29 on wire I35 which connects to contactarm IBI of the switch I 32. The circuit is completed back to the otherside of the high voltage power source through contact arm I 3!, contactsI34 and I 35 when closed, contact arm I33 and wire I35. At this stage ofthe operation, with both switches closed, both the burner motor andignition are energized and in the normal course of operation flameshould occur in the burner. After the predetermined time (determined bythe physical constants of the heater I46 and bi-metal I), the contactarms IIS and I2I) of the switch IIQ will be moved until the contact armI I8 engages the stop I4 3, and upon further movement the contacts I?!and I22. are separated, thus breaking the circuit to the ignitiontransformer I24. If at this point no flame has occurred in the burner,the bi-metal member I45 of the timer I54 will continue to move, andafter predetermined further movement the contact arms I3I and I33 of theswitch I32 will be moved to an overcenter position relative to the snapmechanism I37 and the contact arm I33 and switch contact I35 will moveaway from the contact I34 with a snap movement, thus breaking thecircuit to both the burner motor I 5.32 and ignition transformer I24. Ifflame occurs in the burner It! after the closing of the switch contactsI I and I35 of switch I32, and prior to the re-opening of thosecontacts, the fiame responsive bi-metal I52 will move the contact pole Iof the doublethrow switch I54 and open the contacts I52 and I5'I andclose the contacts I53 and I58 to place the resistor I55 in seriescircuit with the resistance heater I45 for the bi-metal member I45. Whenthe resistor I55 is placed in series with the resistance heater I45, thevoltage drop through the resistor I45 is reduced to a point such thatthe heat output thereof to the bi-metal member I45 is sufiicient tomaintain the same in an actuated position between the point at which thecontacts I2I and I22 of switch I I 9 are opened and the point at whichthe switch I 32 is snapped open. It will be seen then that in normaloperation when the system is required to produce heat, the timing meansfirst causes the switches to be placed in a position to energize boththe ignition and burner motor. After a predetermined time the ignitionswitch is opened and the burner motor circuit remains on. If flame hasoccurred in the burner by this time, the timer mechanism will hold theswitches in this position. Upon deenergizaticn, the ignition switch willfirst close and then the switch I 32 controlling both the burner andignition will reopen (by engagement of contact arm I33 with stop memberI66). The closing of the ignition switch just prior to deenergization ofthe system will cause a momentary ignition at this time and will consumeany residual combustible gases left in the burner. On the other hand, ifflame does not occur in the burner by the time the ignition switch isopened, the timer mechanism moves the switch I32 until the same issnapped open, as previously described, and the burner and ignition areboth shut down by that operation. After the switch I32 has been snappedopen, it is necessary that the contact arm I33 and contact I35 be resetmanually from this safety position and the reset button I40 is providedfor that purpose. It should also be noted that the snap mechanism it!includes an adjustment means such as the screw I39 for the overcenterspring its to vary its relation to the contact arm 133 and thus vary thetime required to move to a safety snapped open position.

From the foregoing descriptions or" the system disclosed herein, it isseen that there is here provided a very simple control system for aliquid fuel burner having a very simple timing mechanism and havingconsiderably less than the usual number of control switches and othercontrol parts therefor.

While there has been described herein only a form of this invention, itwill be obvious to those skilled in the art that other modifications ofthis system are possible without departing from the scope and intent ofthis invention as defined in the appended claims.

Having thus described the invention, what is claimed and is desired tobe secured by Letters Patent of the United States is:

1. In a burner control system, a liquid fuel burner, a burner motor andelectric circuit therefor, an electric ignition means and circuittherefor, a first switch havinginitially closed contacts in saidignition circuit, a second switch connected in series with said firstswitch and having contacts in both said motor and said ignitioncircuits, said second switch having a contact arm and a snap mechanismcooperable therewith operable to cause the same to be snapped to an openposition after actuating movement in one direction through apredetermined range, means cooperable with said first switch to causethe same to be opened after movement less than said predetermined range,electric timing means for actuating said switches, a circuit for saidtiming means, said timing means being arranged to actuate said switchessequentially so that said second switch is closed first, after apredetermined time said first switch is opened, and upon actuationthrough said predetermined range said second switch is reopened with asnap movement, means controlling energization of said timing meanscircuit, and means operable to stop said timing means at a point ofactuation subsequent to opening said first switch and prior to reopeningsaid second switch.

2. In a burner control system, a liquid fuel burner, a burner motor andelectric circuit there for, an electric ignition means and circuittherefor, a first switch having initially closed contacts in saidignition circuit, a second switch connected in series with said firstswitch and having contacts in both said motor and said ignitioncircuits, said second switch having a contact arm and a snap mechanismcooperable therewith operable to cause the same to be snapped to an openposition after actuating movement in one direction through apredetermined range, means cooperable with said first switch to causethe same to be opened after movement less than said predetermined range,electric timing means for actuating said switches, a circuit for saidtiming means, said timing means being arranged to actuate said switchessequentially so that said second switch is closed first, after apredetermined time said first switch is opened, and u on actuationthrough said predetermined range said second switch is reopened with asnap movement, means controlling energization of said timing meanscircuit, and means responsive to the occurrence of fiame in said burnerto stop said timing means at a point of actuation subsequent '5 toopening said first switch and prior to reopen ing said second switch.

3. In a burner control system, a liquid fuel burner, a burner motor andelectric circuit therefor, an electric ignition means and circuittherefor, a first switch having initially closed contacts in saidignition circuit, a second switch connected in series with said firstswitch and having initially open contacts in both said motor and saidignition circuits, said second switch having a contact arm and a snapmechanism cooperable therewith operable to cause the same to be snappedto an open position after actuating movement in one direction through apredetermined range, means cooperable with said first switch to causethe same to be opened after movement less than said predetermined range,electric timing means reversibly actuated for actuating said switches, acircuit for said timing means, said timing means actuating said switchesin said one direction upon energization and in the other direction uponde-energization, said timing means being arranged to actuate saidswitches sequentially so that said second switch is closed first, aftera predetermined time said first switch is opened, and upon actuationthrough said predetermined range said second switch is reopened with asnap movement, a thermostatic switch responsive to the temperature ofthe space heated by said burner to control energization of said timingmeans circuit, and means responsive to the occurrence of flame in saidburner to stop said timing means at a point of actuation subsequent toopening said first switch and prior to reopening said second switch.

4. In a burner control system, a liquid fuel burner, a burner motor andelectric circuit therefor, an electric ignition means and circuittherefor, a first switch having initially closed contacts in saidignition circuit, a second switch connected in series with said firstswitch and having initially open contacts in both said motor and saidignition circuits, said second switch having a contact arm and a snapmechanism cooperable therewith operable to cause the same to be snappedto an open position after actuating movement in one direction through apredetermined range, means cooperable with said first switch to causethe same to be opened after movement less than said predetermined range,electric timing means comprising a bimetallic heat motor and resistanceheater therefor, reversibly actuated upon heating and cooling foractuating said switches, a circuit for said resistance heater, saidtiming means actuating said switches in said one direction uponenergization and in the other direction upon de-energization, saidtiming means being arranged to actuate said switches sequentially sothat said second switch is closed first, after a predetermined time saidfirst switch is opened, and upon actuation through said predeterminedrange said second switch is reopened with a snap movement, athermostatic switch responsive to the temperature of the space heated bysaid burner to control energization of said resistance heater circuit,and means responsive to the occurrence of fiame in said burner to reducethe heat output of said resistance heater to said bimetallic heat motorto a point operable to maintain the same in an actuated position lessthan the predetermined range of movement required for reopening saidsecond switch.

5. In a burner control system, a liquid fuel burner, a burner motor andelectric circuit there- 7 for, an electric ignition means and circuittherefor, a first switch having initially closed contacts in saidignition circuit, a second switch connected in series with said firstswitch and having initially open contacts in both said motor and saidignition circuits, said second switch having a contact arm and a snapmechanism cooperable therewith operable to cause the same to be snappedto an open position after actuating movement in one direction through apredetermined range, means cooperable with said first switch to causethe same to be opened after movement less than said predetermined range,electric timing means comprising a bimetallic heat motor and resistanceheater therefor, reversibly actuated upon heating and cooling foractuating said switches, a circuit for said resistance heater, saidtiming means actuating said switches in said one direction uponenergization and in the other direction upon de-energization, saidtiming means being arranged to actuate said switches sequentially sothat said second switch is closed first, after a predetermined time saidfirst switch is opened, and upon actuation through said predeterminedrange said second switch is reopened with a snap movement, athermostatic switch responsive to the temperature of the space heated bysaid burner to control energization of said resistance heater circuit,parallel circuits connected in series with said resistance heater, aresistor in one of said parallel circuits for reducing the heat outputof resistance heater to a point such that said timing means heat motorcannot move through said predetermined distance to reopen said secondswitch, a double throw switch connected to said parallel circuits forswitching between them, and means responsive to the occurrence of flamein said burner to actuate said double throw switch to connect thecircuit including said re sistor in series connection with saidresistance heater.

6. A burner control system as defined in claim 5 including a movablereset member cooperable with said second switch contact arm forresetting the same from said snapped open position.

7. A burner control system as defined in claim 5 including means toadjust said snap mechanism to vary the time of energization of saidtiming means required to snap open said second switch.

8. A burner control system as defined in claim 6 including means toadjust said snap mechanism to vary the time of energization of saidtiming means required to snap open said second switch.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,674,051 McCabe June 19, 1928 1,876,281 Eiseman 1 Sept. 6,1932 2,012,322 Satchwell Aug. 27, 1935 2,135,829 McGoldrick Nov. 8, 19382,170,426 Haney Aug. 22, 1939 2,261,586 McGrath Nov. 4, 1941 2,593,518Aubert Apr. 22, 1952

